() Field Of The Invention
This invention relates to high temperature self-cleaning ovens, and particularly to an oven door latch mechanism so the oven door may be sealed during a self-cleaning oven cycle, and the door can only be opened after the oven temperature returns to the normal cooking temperature range.
(2) Description Of The Prior Art
The present invention relates to a door latching mechanism for a door of a high temperature self-cleaning oven of the general type as is described in the basic patent of Bohdan Hurko, U.S. Pat. No. 3,121,158 which issued on Feb. 11, 1964, which is also assigned to the present assignee.
Such a self-cleaning oven would have a normal cooking function of baking and broiling within the temperature range between about 150.degree. F. and 550.degree. F., as well as a self-cleaning cycle where the oven air temperature is raised to a maximum somewhere between about 750.degree. F. and about 950.degree. F. for degrading and removing the food soil and grease spatter that accumulates on the walls of the oven liner during normal cooking. Such a reaction may be characterized by the term pyrolysis, which means the chemical decomposition of matter by the application of heat.
The present invention is concerned with means for ensuring that the oven door is both closed and latched before the self-cleaning oven cycle can be initiated, as well as to ensure that the oven door cannot be unlocked as long as the oven air temperature is above the maximum normal cooking temperature.
An early patent in this art is U.S. Pat. No. Re. 26,944 to Clarence Getman, which is also assigned to the present assignee. This Getman patent discloses a self-cleaning oven with a manual door latch mechanism, and automatic means for locking the latching mechanism. A solenoid is furnished and it is capable of overriding the locking means so that the door latching means may be operated. The solenoid control circuit is governed by a momentary switch and a thermostatic switch that is opencircuited above normal cooking temperatures.
An early attempt to replace the solenoid locking system for the door latching mechanism is described in the William Fane U.S. Pat. No. 3,362,398, which is also assigned to the present assignee. This patent utilizes a thermally responsive locking means for engaging the door latching mechanism. This locking means is represented by a bimetal disc positioned within the oven cooking cavity for operating a pivoted bolt member.
A patent showing a bimetal-operated door latching mechanism is described in the patent of Jean-Claude Lafforgue, U.S. Pat. No. 3,440,403. This door latching mechanism is not a manual latching mechanism but one that is controlled by a large bimetallic member. A heating element is arranged adjacent the bimetallic strip so as to give quick response to the latch member.
Another patent showing a thermally responsive locking means for an oven door latching mechanism is described in the patent of James White, U.S. Pat. No. 3,815,942, which is also assigned to the present assignee. This locking means comprises a single-point thermostat having a temperature sensing probe located within the oven cooking cavity. The thermostat has a snap-acting responder which controls a pawl for locking the latch mechanism.
The principal object of the present invention is to provide an oven door latching mechanism for a self-cleaning oven with a thermally-operated locking means which is accurately responsive to oven temperatures above normal cooking temperatures, and which will also unlock the door latching mechanism soon after the cleaning cycle has terminated.
A further object of the present invention is to provide an oven door latching mechanism of the class described wherein the thermally responsive locking means is associated with the oxidation unit of the oven exhaust system.
A further object of the present invention is to provide an oven door latching mechanism of simplified structure with a shifting pivot means.
A further object of the present invention is to provide an oven door latching mechanism of the class described wherein the latch handle may be operated between open and closed positions without the oven being connected to a source of electrical power.
A further object of the present invention is to provide an oven door latching mechanism of the class described wherein the latch will not remain in the circuit actuated position if the oven door is not closed.